Geological Characteristics And Prospecting Prognosis Of Amtan Iron Mine＆Crystal Graphite In Dulan,Qinghai Province

The tectonic location of the study area is located in the north slope of Qimantage mountain to Xiariha Neoproterozoic-early Paleozoic magmatic arc belt.The degree of study in the research area is low,and previous research work is few.Taking Amutan iron polymetallic-crystalline graphite ore as the research object,based on the field geological exploration work and previous research results,this paper summarizes the geological characteristics of Amutan iron polymetallic-crystalline graphite ore,analyzes the genesis of the deposit and makes ore prospecting prediction.Making detailed field investigations of the research area,this paper analyzes that monoclinal fold and torsional fault are the main guiding structure and controlling structure of iron polymetallic ore in the Amutan mining area,and crystal graphite ore is obviously controlled by stratum.The host rocks of the two ore bodies are all kinds of alteration rocks,graphitic schist,amphibolite schist and marble that are only exposed in lower Proterozoic Jinshuikou group（Pt₁j）.This paper analyzes the coincidence of geophysical anomalies with orebody occurrence.Through field identification and thin section analysis,it is concluded that sodium metasomatism develops in the lower part,potassium metasomatism develops in the upper part,mixed sodium potassium metasomatism develops in the middle,and various alteration such as calcium metasomatism of tremolite and actinite,micrite carbonation and petrochemicals widely develop.The relative contents of Au,Cu and Co in this deposit are high through full analysis and electron probe analysis.According to the granulo-zircon U-Pb isotope dating of ore-bearing strata in the Amutan area,the age was 1925.1±4.7Ma,and the stratigraphic markers were determined.Through geological exploration,crystalline graphite ore reserves increased.Summarizing a series of mineralization characteristics including ore-bearing rock,ore-controlling structure,wall rock alteration and zonality,mineral composition of main element ore and trace element composition of ore,it is concluded that the iron mineralization in the proterozoic strata of this area belongs to the type of iron oxide copper-gold deposit,and the graphitization is the type of schist regional metamorphic crystalline graphite deposit.Based on the summary of the geological characteristics,the prospecting prediction is made.